Analysis of Double Layer and Adsorption Effects at the Alkaline Polymer Electrolyte-Electrode Interface

Abstract

In this study, the performance of the anionic electrodes in polymer-based alkaline fuel cells is analyzed. Direct alcohol, alkaline fuel cells suffer from a rapid decrease in cell potential at low discharge currents. Several effects are described to account for this drop in cell potential. Quaternary ammonium ions can specifically adsorb on the catalyst surface decreasing the active surface area and lowering the rate of methanol oxidation. In addition, the tethering of the quaternary ammonium cations on the polymer electrolyte inhibits the cation mobility causing a diffuse double layer to be formed. The diffuse double layer electrostatically inhibits the migration of hydroxide to the surface of the electrode which is needed for alcohol oxidation. © 2011 The Electrochemical Society.